'\" et
.TH SETJMP "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
setjmp
\(em set jump point for a non-local goto
.SH SYNOPSIS
.LP
.nf
#include <setjmp.h>
.P
int setjmp(jmp_buf \fIenv\fP);
.fi
.SH DESCRIPTION
The functionality described on this reference page is aligned with the
ISO\ C standard. Any conflict between the requirements described here and the
ISO\ C standard is unintentional. This volume of POSIX.1\(hy2017 defers to the ISO\ C standard.
.P
A call to
\fIsetjmp\fR()
shall save the calling environment in its
.IR env
argument for later use by
\fIlongjmp\fR().
.P
It is unspecified whether
\fIsetjmp\fR()
is a macro or a function. If a macro definition is suppressed in order
to access an actual function, or a program defines an external
identifier with the name
.IR setjmp ,
the behavior is undefined.
.P
An application shall ensure that an invocation of
\fIsetjmp\fR()
appears in one of the following contexts only:
.IP " *" 4
The entire controlling expression of a selection or iteration
statement
.IP " *" 4
One operand of a relational or equality operator with the other operand
an integral constant expression, with the resulting expression being
the entire controlling expression of a selection or iteration statement
.IP " *" 4
The operand of a unary
.BR '!' 
operator with the resulting expression being the entire controlling
expression of a selection or iteration
.IP " *" 4
The entire expression of an expression statement (possibly cast to
.BR void )
.P
If the invocation appears in any other context, the behavior is
undefined.
.SH "RETURN VALUE"
If the return is from a direct invocation,
\fIsetjmp\fR()
shall return 0. If the return is from a call to
\fIlongjmp\fR(),
\fIsetjmp\fR()
shall return a non-zero value.
.SH ERRORS
No errors are defined.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
In general,
\fIsigsetjmp\fR()
is more useful in dealing with errors and interrupts encountered in a
low-level subroutine of a program.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIlongjmp\fR\^(\|)",
.IR "\fIsigsetjmp\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<setjmp.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
